Correspondence Comment on “Co-Occurrence of Triclocarban and Triclosan in U.S. Water Resources” This paper followed a previous paper (2004) by the same authors Halden and Paull (1). The first paper (1) included several important observations that are not apparent in the second paper (2), which are crucially important for the interpretation of the 2005 paper. Quotes from the first Halden and Paull (2004) (1) paper: “Six of 26 (23%) urban streams tested positive for triclocarban (TCC) at an estimated detection limit of 25-30 ng L-1... Since all urban sampling stations were located upstream of wastewater treatment plant inputs, the detection of TCC in river water was interpreted as an indication of raw wastewater inputs from leaking sewer lines. The 90-year old sewer system of Baltimore City is known to leak wastewater in many locations, requiring upgrades at costs estimated at $ 1.3 billion... Previous TCC data ranged from 240 ng L-1 in U.S. surface water to 50 ng L-1 in wastewater (TCC Consortia, 2002)...The discrepancy (to measured concentrations in the Baltimore area) may be due to... (iv) sampling (TCC Consortium, 2002) in locations that were less impacted by raw and treated wastewater” (1). All these statements are sound; unfortunately, these observations are not transparent in the 2005 paper. The samples taken from the six TCC positive streams were all impacted by illegal discharges of raw wastewater (3). Especially the stream Gwynns Run, which contains up to 99% raw sewage (4). The authors compared and found similarities between triclosan (TCS) and TCC and in Figure 2 (2) found a oneto-one relationship between the two in 42 environmental samples from the Greater Baltimore region. These findings are extrapolated to the rest of the United States based on Kolpin et al. (2002) (5) findings of TCS in the United States Geological Survey (USGS) survey. Kolpin et al. (2002) “used consistent protocols and procedures designed to obtain a sample representative of the streamwaters” - across the U.S (5). Many of these were worst-case scenarios, but none were impacted by known illegal discharges and significant amounts of raw sewage. The correlation of TCC and TCS concentrations from analyses of influent, effluent, and sewage contaminated surface waters from the Baltimore area by Halden and Paull (2005) (2) and comparison with the TCS data of Kolpin et al. (2002) (5) leads to mean and median TCC concentrations in U.S. surface waters predicted to be 213 and 109 ng L-1. TCC effluent concentration from of Baltimore’s wastewater treatment plants is 110 (( 10) ng L-1 (2). These concentrations support surface water monitoring studies reported in the TCC Consortium report (2002) (6), which range from the highest concentration among 113 freshwater location ) 228 ng L-1. The predicted environmental concentration (PEC) based on the USEPA model E-FAST is 1.3-50 ng L-1 depending upon model scenario. The reason for the higher measured concentrations is likely that the selected sites were chosen because they were prone to exposure of industrial and household chemicals (6). It is important to note that the predicted environmental concentrations of TCC would be far lower if Halden and Paull (2005) (2) had used the most recent study by the USGS or the Kolpin et al. (7) study as the source of TCS data where the detection limit and frequency of TCS were only found at low flow, at a 10% frequency, and at a max. concentration of 140 ng/L. The levels found in surface water by the TCC Consortium (6) are confirmed by Halden and Paull’s analysis of findings up to 240 ng L-1 (2). The 6.75 µg L-1 finding is not representative, as this is the same amount found in raw sewage (6.70 µg L-1), and the stream is 99% raw sewage (4). This leads us also to seriously 6334
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doubt the validity of the extrapolation since the parent data are significantly biased. Hence, the title (Co-Occurrence...) and main conclusions (“the magnitude and frequency of TCC contamination, determined in the (present) study, are reason for concern”) in the more recent Halden and Paull paper (2) are not scientifically valid. In summary, the results and amounts reported in the 2005 paper (2) are based on streams with illegal discharges and very significant amounts of raw sewage (up to 99%). The extrapolation is thus not based on representative data and is not valid. Hence, the conclusions about TCC having a detection frequency of 60% and maximum concentration of 6.75 µg L-1 across the United States is highly doubtful and contradicted by the USGS findings in a recent more in-depth survey of the state of Iowa (7). It is surprising that the reviewers were apparently unaware of the USGS work and the previous Halden and Paull paper (1) that contained sound judgments of the streams and explanation of the results. Hence, the title, abstract, and main conclusion of the paper by Halden and Paull (2) are misleading. The real problem was not the TCC levels but the lack of proper wastewater treatment in compliance with state and federal laws and regulations, which resulted in a $1.3 billion settlement (to be invested in wastewater treatment infrastructure over 10 years) between the city of Baltimore and the State of Maryland and the United States (3). The conclusion from the literature is that surface waters likely have TCC concentrations in the low ng L-1 levels, with a detection frequency of 10% (assuming the TCC mimics TCS) (7) with a risk quotient of 0.1-0.3 (6). Or are all U. S. water resources really impacted by illegal discharges of untreated wastewater (roughly 99% v/v)? If so, TCC levels are the least of society’s immediate water problems.
Literature Cited (1) Halden, R. U.; Paull, D. H. Analysis of triclocarban in aquatic samples by liquid chromatography electrospray ionization mass spectrometry. Environ. Sci. Technol. 2004, 38 (18), 48494855. (2) Halden, R. U.; Paull, D. H. Co-occurrence of triclocarban and triclosan in U.S. water resources. Environ. Sci. Technol. 2005, 39 (6), 1420-1426. (3) United States of America and the State of Maryland plaintiffs v. Mayor and city council of Baltimore, Maryland, defendant. 2002. http://www.usdoj.gov/enrd/baltimorecomplaint.pdf. (4) Halden, R. U. Sewage in Baltimore. 2003. http:// www.jhsph.edu/Dept/EHS/Faculty/Halden/ Full_BSSOC_Report_2003.pdf. (5) Kolpin, D. W.; Furlong, E. T.; Meyer, M. T.; Thurman, E. M.; Zaugg, S. D.; Barber, L. B.; Buxton, H. T. Pharmaceuticals, hormones, and other organic wastewater contaminants in U.S. streams, 1999-2000: A national reconnaissance. Environ. Sci. Technol. 2002, 36 (6), 1202-1211. (6) High Production Volume (HPV) Chemical Challenge Program Data Availability and Screening Level Assessment for Triclocarban, CAS# 101-20-2; TCC Consortium, 2002. http://www. epa.gov/chemrtk/tricloca/c14186.pdf. (7) Kolpin, D. W.; Skopec, M.; Meyer, M. T.; Furlong, E. T.; Zaugg, S. D. Urban contribution of pharmaceuticals and other organic wastewater contaminants to streams during differing flow conditions. Sci. Total Environ. 2004, 32, 119-130.
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2005 American Chemical Society Published on Web 07/20/2005
